Front pipe technical question

[BBoarders]

I know there have been a lot of threads about front resonator delete and making the FL5 similar to the ITS from the down pipe aft. I am considering the delete along with a rear motor mount at the same time.

My question has to do with retail offerings available as a replacement. They advertise a 3inch outside diameter to replace the 2.37 inch OEM outside diameter and that they will “optimize airflow” or be “less restrictive.”

If these pipes just connect right up to the OEM mid pipe, won’t that create a bottleneck and defeat the purpose?

Before I pull the trigger I am hoping someone can explain this to me.

Thanks!

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[apl360]

You’re not wrong. The stock portion after the front pipe will be a restriction. It will be less of a restriction in the whole system due to the bigger front pipe though

on stock dp, the k20c1 seems to really do well with a 3” cat back. The gains are pretty solid. Regrettably, the majority of cat backs are so over priced.

 

[MAFL5R]

I know there have been a lot of threads about front resonator delete and making the FL5 similar to the ITS from the down pipe aft. I am considering the delete along with a rear motor mount at the same time.

My question has to do with retail offerings available as a replacement. They advertise a 3inch outside diameter to replace the 2.37 inch OEM outside diameter and that they will “optimize airflow” or be “less restrictive.”

If these pipes just connect right up to the OEM mid pipe, won’t that create a bottleneck and defeat the purpose?

Before I pull the trigger I am hoping someone can explain this to me.

Thanks!

You’re not wrong. The stock portion after the front pipe will be a restriction. It will be less of a restriction in the whole system due to the bigger front pipe though

on stock dp, the k20c1 seems to really do well with a 3” cat back. The gains are pretty solid. Regrettably, the majority of cat backs are so over priced.

I know this doesn’t really answer your question but I put on a MXP front pipe and a HKS Legamax exhaust. The combo is so good. I would honestly just invest in an exhaust and front pipe and not go frankensteining the exhaust with the valve system. That was the whole reason I wanted all of the stock pipes out of there.

 

[blueroadster]

Exhaust gasses would go through a Coffee straw (OEM DP outlet is 53mm or 2.09" ID) --> Big Gulp Straw --> Coffee straw (OEM exhaust output).

If you simply want a better sound out of the OEM exhaust, the front resonator delete will get you that for cheap. If you want better flow to reduce exhaust constipation, I'd suggest upgrading the DP with one that has a larger outlet followed by installing an aftermarket front pipe and exhaust of your choosing to closely match the ID of the DP outlet itself.

Here is a thread for reference where I decided to go with the TSP downpipe mated to a Fujitsubo SS front pipe and titanium exhaust. Keep in mind that SS pipe has twice the wall thickness of titanium.

 

[BBoarders]

I really appreciate all the info from you guys.
I am just looking for a slightly better sound and for how I drive it for the last 2.5 years, it already performs great, stock. So much fun.
I was mostly worried that allowing it to breathe better, and then closing the door, so to speak, downstream could cause some problems for it. I believe the straw analogy answers that question.
Thanks again.

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